Base-catalyzed Degradations of Carbohydrates. V. The Conversion of 3-Deoxyhex-2-enopyranoses into 2-Furoic Esters

Abstract
Condensation of 2,3,4-tri-O-acetyl-α-D-xylopyranosyl bromide and benzyl 2,3,4-tri-O-methyl β-D-glucopyranoside (2), followed by removal of protecting groups, affords 2,3,4-tri-O-methyl-6-O-(β-D-xylopyranosyl)-D-glucopyranose (5). Alkaline degradation of the disaccharide 5, followed by treatment with dilute acid, furnishes 5-β-D-xylopyranosyloxymethyl-2-furaldehyde (8), which is converted by oxidation and esterification, followed by acetylation, into methyl 5-(2,3,4-tri-O-acetyl-β-D-xylopyranosyl-oxymethyl-2-furoate (11), whose structure has been confirmed by direct synthesis.